I left a pot of beer, onion, and butter on the stove to boil with the intention of making beer brats, then stepped away to do something and thought I'd turned off the burners. I had not. I did not realize I had not until I re-emerged 40+ minutes later and the entire room was filled with smoke. The weird part was that despite the smoke being choking thick none of the smoke detectors had gone off, and we had tested them recently. Anyway, took a good few hours to air out the house and two days of scrubbing to clean the burnt onion remains off the bottom of the pan, which had somehow managed to burn while still being submerged in beer. Damndest thing.