When I was in highschool my mother left a pot of stock simmering and went to work, except instead of leaving it on low she left it on high. I came home to a smoke filled apartment, and the pot was full of chicken bone shaped black carbon. As I grabbed the handle and brought it toward the sink molten metal poured out of the heavy base into the sink. It was scary and I’m grateful I wasn’t severely burned and that our place didn’t burn down!
I discovered the hard way when I had my own business with me as the only employee that if you leave a coffee machine with only a small amount of coffee in it on overnight, there will be no fire.
But good luck trying to get the smell of burnt coffee out of your office for the next week.