Search terms used: A lot of variations on heating metal boxes and shipping containers. After that, I tried searching about the survivability in those sort of conditions. Unfortunately, I wasn't quite sure how to phrase that last one. "Person trapped in hot metal box"/"How long can a person survive in a large oven" was not helpful.
Scenario in question: I have a supporting character who is captured by the enemy. Supporting character is under the protection of a character that, while very powerful, is composed almost entirely of water. So, aforementioned enemy needs to find some place to store this character where powerful-water-entity can't easily get to them without some help and planning.
I initially thought of a very hot prison cell. Maybe some sort of metal box. Randomly having that sort of thing on hand seems unlikely, though. I suppose I could go back and establish it earlier as some means of punishment and/or execution for criminals. Or I could just have them quickly wheel in some sort of shipping container for the occasion. (I'd probably go with the former.)
But then I got to thinking about it. If it's hot enough to evaporate water rather quickly, what sort of condition is my supporting character going to be in? The amount of time he spends in there is pretty flexible, since the rescue team goes into action the same day. As long as he survives, I'm not too worried about any injuries he sustains. (I do need him to permanently lose his hearing during this series of events, but it doesn't have to be because of this... though, if I could combine the two, that might be nice.) This all happens around the ending, so I won't need him doing anything any time soon.
I'm not set on random metal box, so any ideas and aftereffects would be oh-so-welcome.