Is there a trope for when every single song in a soundtrack is about the same concept?

I'm trying to make a page for Foamstars, and one thing I noticed is that every song (except one) has lyrics that are about baths, bubbles and foam. But I can't find any trope for this concept, when everything is based around a singular theme. Either for music or even the whole concept.

There's Central Theme but that's about when a work has a message it wants to convey, rather than a concept it's about.

Can anyone help with this?

You should use Trope Finder for such questions next time, but you may be looking for Concept Album. (If that's not what you're looking for, you should still go to Trope Finder.)