I fell into one of those Internet rabbit holes. Immersion cooling for servers with liquid that boils in contact with the hot spots. 3M makes some materials used for fire suppression and cooling that are good for this. Here is a DIY example with a board laid on the bottom of a fish tank. Here’s is a forum posting about a bit coin miner that uses this technique. This video gets into some of the details about how to get better boiling. Lots of interesting heat transfer problems. In time will change entirely how electronics is packaged. For example I bet people are working on using this stuff in laptops. That last one is from a guy at 3M who has a facebook page about their research. Here’s a video where the actual chip is exposed and you can see the hot spots on the chip. Searching on Google for immersion cooling videos will turn up more examples.
These systems use one of variants of 3M’s Novec. It costs a few hundred dollars per gallon.