Made of Explodium: No, not really. Many, many engineers work very, very hard to ensure that this thing? Does not happen.

Two main exceptions:

One, antimatter cryocels. Because, well, antimatter, and despite the aforementioned engineers’ best efforts there’s only so much you can do to stabilize stuff that will explode the moment it touches anything. This limitation is why lighthugger starships, which use megatons of the stuff, do not come into the inner system under any circumstances, or near any important planets/habitats in the outer system, either!

No-one wants to accidentally lose a continent, y’know?

Two, stargates. Which bend spacetime in really unnatural ways, and are powered by a large contained singularity.

Now, it’s very hard to get to their explodium, seeing as they come with a very complete set of automaintenance, self-repair, and self-stabilization systems, in addition to having outer shells Made of Indestructium such as fancy singularity-locking (handwaaaave! explained tomorrow) anti-energetic armor and some of the thickest regular composite armor plate anywhere, such that if you should scrape, bounce, or ram it with a regular starship you’ll just smear yourself out over its surface and the local Ring Dynamics rep will be very ironic at you.

On the other hand, if you do manage to get through said indestructium, you will rapidly learn that the reason they’re made of it is that when they go unstable, they explode on a world-shattering, star-system-sterilizing scale. (Which, of course, is what necessitates the indestructium in the first place. Without that, even as the only practical form of FTL travel anyone’s come up with, no-one’d allow them anywhere near their star systems.)