I think there's one very important thing that others have missed. In my life, I've found this is the answer 99% of the time. I'm very passionate about sharing this thought.
I have a rule: when in doubt, turn the conversation back on the other person or mirror their statements.
Them: "I can't believe FC Dynamo Kiev lost their last match"
You: "Me either, that last goal was embarrassing" then, turn it back on them "Where did you watch the game at?" or "Can you remember a worse loss?" **
Conversations aren't just statements back and forth, it's about two people interacting emotionally. What emotion are they expressing during your conversation? Are they bored, angry, upset, sleepy? Figure out that emotion, and steer your own statements in that direction.
Does the person want to keep talking? Are they saying few words? Are they facing away from you? They might not want to talk anymore, as the other answers said. They might be tired and want you to do more talking. Do they like the topic you're on? Do they show more interest when you mention a different topic? Are they focused on something? A picture, their watch, the sky? What might they be thinking about?
Keeping your mind externally focused makes conversation easier More info on that