"There is some liquid in the glass."
Translation:В стакане какая-то жидкость.
Hmmm. In English, 'some liquid' sounds partitive (as in there is some of something in the glass), whereas какая-то means more like 'some kind of' in Russian, no? There's a big difference in meaning between 'some' and 'some kind of' in English. Am I wrong in thinking that какая-то means 'some kind of' here?
No, you're not wrong. The meaning is 'some kind of' here.
On the other hand the dictionary has this meaning right after "unspecified amount":
determiner: some 1. an unspecified amount or number of. "I made some money running errands" 2. used to refer to someone or something that is unknown or unspecified. "she married some newspaper magnate twice her age"
Yes, the second example in the definition means the same thing as some kind of, as she married some kind of magnate, not some (a quantity) of magnates. This is not the same as there is some water in a glass, which means a quantity of water. No native English speaker would think 'some water' means some kind of water, whereas in Russian, какая-то means some kind of.