Once upon a time in our last office someone decided to put their slice of pizza in the microwave to warm up. Nothing wrong with that you may think, but it was still in a cardboard box. Still not too bad? The box was just big enough to fit in the microwave, but not rotate. And then they put it on for a too long amount if time and pissed off somewhere. The smell of burning made its way to some nearby desks where the occupants then went to investigate. Somehow it didn't set off the fire alarm!
In the current office we now have some full-on industrial strength microwaves, which don't have a turntable. The catch with these is that they're quite powerful and some staff ignore the warnings, plonk their food in and then set the amount of time they usually do at home. Well within half of that time what ever is in there starts bubbling over and spreading (see 80s B movie The Stuff).