I'm not quite sure what you mean by "concept album", but from my point of view this should be a release with connection between the songs serving an entire idea. Hope I'm right 🤣🤔
In this sense, a great album I can think of is Björk's Vespertine from 2001. This album was designed to sound more intimate and domestic compared to her work so far. Plus it was produced in a time where the Napster platform for downloading mp3-files was at its peak, so Björk wanted to use sounds difficult to be compromised when downloaded on a PC - harp, celesta, clavichord, strings, even household sounds like shuffling cards, ice being cracked or snow being trampled by boots.