According to dictionaries, "some" can sometimes mean "a large number or amount of something". This is while "some" is mainly used to mean "an amount or number of something that is not stated or not known". Now the question is: how can we know that in a sentence like the one below "some" means a considerable amount, not an unspecified amount?
Oxford Advanced Learner's Dictionary uses the following example for "some" as "a large amount of something":
It was with some surprise that I heard the news.
There's a similar example from Merriam-Webster's Learner's Dictionary:
Their decision was met with some surprise.