Well, for the Mysterious Liquid specifically, it's completely random. So it's impossible to tell what it will do. You get it when you do not successfully synthesize a chemical in the lab.
If there's a stat screen, it could be, say, a room in the decaying building that has some sort of fitness analysis machine, maybe also solar-powered in some way so that it's not necessary to use batteries (but with the setup being far too big and heavy to carry back to the base). That way you get to show all relevant stats to the player (like strength and fluid volume out of max, for example) without making it easy to micromanage the hell out of it, and it would fit decently in the game's own story.
For this specifically, I mean a short text whenever you consume it, so you can tell what it's done to you. The randomness is perfectly fine, but being able to know what it's done when you take it would be a good idea in my opinion, since right now it's hard to know exactly what it can do in the first place.