How does water suspended in more water not boil? ( I think it can be called a double boiler )

Question

I found this TikTok but I didn’t quite grasp it. https://vm.tiktok.com/ZMYFDecSL/

In: 3

Answer 1

It’s basically a “heating brake”:

If the big pot gets above 100, water evaporates, taking heat away, restoring the 100. The result is that the suspended container can’t ever get above 100.

The whole purpose is to guarantee you don’t burn what is in the suspended container. Very good to melt chocolate without paying too much attention. And you can get away with not stirring it.