Coolant leak/possible over heating

What is your question?

Car started smelling warm but temp gage didnt move. When i parked there was a puddle of water under my car and the radiator was empty. There was water in the overflow and the top had popped off the overflow due to pressure. Car only leaks when it is running. What could the issue be

What makes this problem better or worse?

Leaks when car is running

How long has your 2003 Kia Rio had this problem?

started three days ago