Loud Popping Noise after driving over a bumpy railroad track

My daughter was driving home last night and she said that she noticed a noise coming from the car after she went over a bumpy railroad track. It makes a very loud popping noise that is noticeable going straight or turning. She probably drove it about fifteen miles after that to get home. I was going to drive it to see what she was hearing. Our driveway has a slight slope and I noticed it backing out and when I started forward. I only drove it about ten to fifteen feet and the noise was very noticeable so I did not go any further and parked back in the driveway. I am not sure that it would be considered drive-able to the shop. If the repair is very expensive, it will not be made as the car is old, high mileage and my daughter will be going to college next fall.