If you put a singular countable noun after "some", then you will be talking about a single thing, and it either means that the thing is a BAD example of the noun, or that it is an example that you don't understand.
Here's an example where the thing is a BAD example of the noun.;
"He came to the party with *some woman*. She smelled bad, and she ruined every conversation she tried to join.I hope I never see her again."
Here, the "some" is an insult. It means that you could pick any random woman, and she would be better than the woman at the party.
Here's an example where the "some" means "an example that you don't understand."
"The burn marks seem to show that Bob was killed with *some kind of laser.* I've never seen a laser powerful enough to kill a person, but only a laser could make those kinds of burn marks. I'm confused."