I forgot to turn off the stove with some pork and sauerkraut on low heat, and went out drinking. Many hours later I came back to a smoke filled house, with a pot filled with solid charcoal that ended up in the trash because I just couldn't get it clean enough. I had to trash a couple things in the cabinets above the stove, because I couldn't get the smoke taste out.

More recently, I preheated a pan too much to sear a steak. I always wondered what kind of idiot starts a grease fire, now I know. The avocado oil took about 5 seconds to ignite, and it ended up destroying a splatter screen I'd set on the pan from the rapid temperature change. Luckily I remembered to cover the fire to put it out.