... would you rather have the powers of Batman or Superman? That's an interesting question. And probably not what you expected. But I'm sure there would be a lot to talk about it no matter which answers you'd choose.
Questions are funny things. They are good conversation starters and can keep any conversation going on. And it doesn't have to be as obscure as my example. Just simple things can ignite a meaningful conversation. You just need to keep asking them.
The key point is to keep the questions open-ended. Asking a bunch of yes / no questions gets boring really fast. But asking the other to explain their reasoning can carry the conversation a long way.
But when you start asking questions you need to remember to give your conversation partner the time to ask questions for you in turn as well. It goes both ways. And if they don't you can ask if they would like to hear your opinion for example.
And once the conversation is rolling smoothly you should pay attention to what the other is saying and expressing your understanding by asking questions that are related to the matter they are telling you. Showing both that you understand and that you care.