Will the substance dissolve in water, hexane, both or neither?

What substance?

Try it, and let us know.

THE substance! Alchemy perhaps? Lead? Methyl Chloroform? U-235? The best answer so far is "maybe".

Will the thingy explode in the microwave? Depends on the thingy. In this case it would depend on what substance you're talking about. There are too many substances for us to guess which one you're asking about.