In the words of your friendly local blast physicist, “Well, ravioli isn’t a gas, but under enough pressure, ravioli behaves as a gas.”
This is a discussion of the question “Would a chunk of metal (can of ravioli) impacting another, larger, rest mass structure (star destroyer) produce an ‘explosion’ effect, or simply punch an appropriately shaped hole as it passed through?”
Let’s c what happens towards the end:
At around .985 c (Cerenkov 1.2 or so), the ravioli now weighs twice what it used to weigh. For a one pound can, that’s two pounds... or about sixty megatons of excess energy. All of it turns to heat on impact. Probably very little is left of the space-cruiser.
At around .9998 c, the ravioli radiation beam is still wimpy as far as nuclear accellerator energy is concerned, but because there is so much of it, we can expect a truly powerful blast of mixed radiation coming out of the impact site. Radiation, not mechanical blast, may become the largest hazard to any surviving crew members.
Here’s a footnote for the end-conditions:
According to physicist W. Murray, we may also expect raining frogs, plagues of locusts, cats and dogs living together, real Old Testament destruction. You get the idea...