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

Water does not instantly boil at 100 C, as in you can have liquid water at 100 C. To actually make the water turn to gas you have to keep pumping more energy into it.

This is what the burner at the bottom is doing, providing more energy to turn the water to gas. This is why the water at the bottom is what turns to gas and then bubbles up, causing what we call boiling.

The water that is up in the second container is not exposed to that energy getting added, because it’s away from the burner, it is only exposed to the water around it. That water around it is only at 100 C, meaning the water in the container can only get to 100 C, but cannot boil because there’s no more energy to add to it. It’s away from the burner.