Funny story...but almost NOT a funny story.
I had set up my sous vide cooker and had just dropped the pouch in the water bath. The temperature of the cooker started rapidly rising. I was looking through the manual for the damn thing, figuring I did something wrong, when I saw the heating element inside glow BRIGHT red and then burst into flames!!!
Thankfully I was standing right next to it, and unplugged it. I tossed it into the sink and hosed it down with water.
Scared the crap out of me!! For the record, it was one of these.