My trick for when I'm in one of these conversations: after answering, ask "and what about you?". That is of course assuming the question is applicable to them (eg. "do you play any sports", but not "where did you get that shirt").

That way, you show that you are interested in the conversation and the other person. And often with these open-ended questions, people ask them because they have a good answer. (I know it seems narcissistic, but asking yourself "what question would I like asked of me" can be a good way to come up with questions.)