I just discovered this double-walled camping kettle. It’s called the Kelly Kettle. You build a fire in the base and the flames rise up and out of the hollow interior. The double wall holds a pint of water. (There are larger size up to 1.5l) The water boils in 3 to 5 minutes. The fact that it looks like a blow torch once you light it is an added bonus.

Here’s a review on Cool Tools.

Here’s the company’s site.

And here it is on Amazon.