Michael Swan (Practical English Usage, 2005.539-40) writes, "Both some and any can refer to an indefinite quantity or number.[...] Some is most common in affirmative clauses. Any (used in this sense) is a 'non-affirmative' word, and is common in questions and negatives. [...] The differences between somebody and anybody etc are the same as the differences between some and any.'
While there is truth in this, many readers take the remarks about 'some' being common in affirmative clauses and 'any' being comon in questions and negatives to be 'rules'. they are not.
Michael Lewis, In (The English Verb, 1986.34) is perhaps clearer" 'Both some and any are used with indefinite reference.
Some is used if the idea is restricted or limited in some way.
Any is used if the idea is unrestricted or unlimited.
[...] the restriction may be a real one [...]or a psychological one existing only in the mind of the speaker.'
So, according to Lewis,
I like some pop music is limited - 'some' implies that the speaker does not like all pop music.
I like any pop music is unlimited - 'any' implies that the speaker likes all pop music.
I don't like some pop music is limited - 'some' implies that the speaker does not dislike all pop music.
I don't like any pop music is unlimited - 'any' implies that the speaker dislikes all pop music.
- For Teachers