In my case the dishwasher's program cycle got stuck and it kept heating up the water till it had all evaporated.

I would usually nudge it along when it got stuck, but that time I had been out and forgot about it. I would have never expected that to happen but in hindsight I feel pretty stupid for not replacing the dishwasher immediately when it started acting up.

To be honest, I'm not sure. I can say for a long time, refrigerators were very dangerous and would often kill people. It's why Einstein co-patented a new mechanism for refrigeration.

Likewise, maybe there's something particularly challenging about designing heating elements to work in a watery environment that makes dishwashers subject to failure.

It also doesn't have the same global popularity as more common appliances like a dryer, so perhaps the failure rates aren't as well known, except among the affluent and restaurant owners.

Maybe unsecured plastic falling onto the element prior to the dry cycle.