If asking in the context of starting a conversation with someone we use "anywhere" more than we would use "somewhere" so we say "Did you go anywhere interesting this weekend?" "Any" is not specific. "Some" is more specific so to ask if you went somewhere also holds the idea that you think they went somewhere specific. So... "Did you go somewhere specific this weekend" has a subtext that silently says something like, "I know you went to the beach without me!" But did you go "anywhere" indicates you have no idea if they did and are just curious.