So when I try to park in a spot to the right I turn the wheel all the way and hear a loud POP! When I go left I hear a creaking noise.

I haven't gotten a chance to check what it could be but from what I know its either the:

1. Control arms
2. CV Axles
3. Steering rack

How can I tell which one it could be and what should I check first?

 

Had the same problem with my old a6 and the steering rack ended up needing to be tightened. This happened around 60k miles for me. I would start with making sure yours is good and tight. It's cheap to have done or free if you can do it yourself. Hope this helps. Good luck!

 

Lift the car and shake the wheel left and right and up and down for any play. More than likely a bushing on the control arms is worn/gone.

 

agreed. does the car also "hop" when the pop sound occurs while reversing?

 

Sounds like a ball joint

 

I don't think so. I haven't noticed anything unusual in reverse