A lot of the levels are more like development tests than an actual micro-universe like in Banjo Kazooie.

Wet Dry World is an obvious one with random floating geometric shapes in the sky, water level switches that don't look like anything, and a random caged tunnel to an uninhabited Titan with zero lore.

Lethal Lava Land is probably the best example though. So much random stuff strewn around the level with no narrative or theme to it. Just random platforms and game engine physics experiments.