Microwave ovens are an example of this. The microwaves are "tuned" to resonate with one of H2O's unique vibrational modes. I can't remember if it is one of the stretching or flexing modes, but you get the idea.

That's why many dry things (paper) don't heat up.

As to why the MP's are so whatever; I'd say each substance that melts results from a unique combination of atomic and molecular forces that hold it together. Hydrogen bonding is a very common one of these forces.

Corrections anyone??
...I'm just going on long ago memories.

~samwik

Pyrolysis creates reduced carbon! ...Time for the next step in our evolutionary symbiosis with fire.