A few years ago, my father's propane bbq/grill blew up into a fiery inferno that was 6-8ft tall.

No one was hurt, but it was seriously scary and now I'm completely wary of grills, especially if they make
any type of hissing/sizzling sound, which is basically normal 'cooking on a grill' sounds.

BG; He had one of those grills with an attached cover on top that you lifted up, a side hot plate, and a propane tank tucked underneath it, hidden behind two little doors that had a small wire shelf attached to them to keep your cleaning gadgets and/or cooking utensils. We have a back porch, which is mostly covered by some overhang/ceiling and is not enclosed at all, so he usually just pushes the grill out to the edge of the cement and grills there. There's about 2-3 feet of cement past the overhang. When not in use, he keeps the grill in the corner of the porch, against the house.
So, dad had grilled dinner (probably some chicken), brought it inside and of course had thought he had turned off the grill. We ate while watching TV. So 30-60 minutes later, dad goes outside for some reason.* A forgotten plate, the bottle of BBQ sauce, something small.. and then he checks the grill so that he can pull it over to the corner. It was highly unusual for me to do so, but I followed him out and stood in the doorway of the garage, watching him, probably having a conversation with him. I was 12 feet away from the grill or so. He moves it about 6 inches and sees a black chunk of something on the ground. He bends down to look at it and 'thinks' it is the rubber tubing for the propane connection, so he crouches down to open the little doors to see and next thing I know,
WHOOOOOOOOOOOSH, the entire grill is engulfed in flames as tall as the porch ceiling, licking the edging of the roof there. Dad, to his credit, managed to shove the grill back a couple inches as he
jumped up and away from it. I asked him if he was ok and he said he was, then the grill popped and like.. another coat of flames shot up, like someone had tossed flammable stuff on it.*
Dad told me to go get the fire extinguisher we have in the kitchen, and I ask if we should call 911. He doesn't answer, so I just run in to get the extinguisher. We also have large sliding glass doors to our porch (which we were not using this time) and you could see this blazing fireball through the thin curtains. Mom was sitting not 3 feet away from the window and
had not noticed anything, but heard the explosion. So of course she asks me what the sound was and I brilliantly answer "uh... don't look out the window."

She must have looked out the window to see the problem, because she went outside to give dad the extinguisher as I asked her if we need to call 911. She returns to tell me, yes, I should call and goes to find our cats, in case we need to grab them and leave the house. Well, I'm already freaking out internally and I'm one of those people that just does
not like using the phone, but I manage to call properly despite all that and calmly answer everything. There's a firehouse pretty much 4 streets over from our house, so we pretty much heard the sirens as soon as the operator person ended the call. I opened the garage door, then check on dad, only to find that our next door neighbor had run over with his garden hose, spraying it at the grill while dad had grabbed ours and was keeping the house/roof edge wet. I went down our driveway to wait for the firemen and several neighbors had come out of their houses, all curious to what's going on at my house. I'm not sure how they knew, since I don't think they could see anything from the front of our house and we live by a semi-main road, so we hear emergency vehicles drive by often, but they started asking me questions and I just ignored them. I think the neighbor's wife might have gossiped it. Anyway, the fire truck pulled up, lights blazing but sound off now and 6 or so fully dressed guys file off and into the garage to get to our back yard... only to find that the fire had finally died out. Turns out that the firemen knew this fireman that also works part time with dad (as coworkers in retail), so they all got to talking for like 20 minutes. I don't know what they discussed, if it was anything relevant to the situation (don't blow up your grill) or if it was just shooting the breeze about the mutual friend.
Dad hadn't cooked on the edge of the cement this time, so it was good that he managed to give it that shove, since even with it, the grill was barely not under the house while aflame. The grill died spectacularly, it was a charred, melted, mess, caving in on itself with holes burned through the cover/sides. The white propane tank was charred black, the nozzle permanently disfigured. A huge scorch mark on the cement. A homemade, wooden flower planter partially scorched, the plant within half burned/killed. The house managed to be unharmed, just some soot that dad washed off later. Most importantly, dad was unharmed, because he was seriously
right there when it went off. Crouched down, had his hands on the grill, peering at the propane tank when everything went to hades.
After all that, mom didn't allow him to have another grill for over a year. To be honest, I don't know that she ever wanted him to get another, but he got one before 2 years passed. I'm not sure how the whole 'getting a new grill' thing went down because I was living elsewhere when the new grill was acquired.
* - Dad had kept a can of cooking spray in that door shelf, so when it got too hot, it blew up too. Yes, he knew he shouldn't have kept it there for exactly that reason, but I guess convenience won out.