Microwaves have a "thaw" function, though it doesn't seem very effective. It is even less effective the larger a block of material.

What's the physics of the result?

I extrapolate that one possibility would be half-raw and half-overcooked, as I've seen that happen in other cases.

*ponder* Or maybe the differences would again be explosive, since some things -- especially potatoes, even diced ones -- explode in microwaves.

And grape halves can make plasma arcs!