what could be causing knock or pop sound from rear of vehicle?

What is your question?

We thought this noise might be the shocks. Replaced the shocks but are still hearing this sound. It's not a constant thing. We tend to hear it when we turn and sometimes if the road is bumpy or rough. It's not anything inside the vehicle. Sounds like it coming from the rear or the vehicle but not sure if it's on the left or right or both. Just frustrating.....vehicle drives fine but, would like to stop this sound. Thanks.

What makes this problem better or worse?

not affected by anything we do/don't do; not a constant sound

How long has your 2015 Toyota Sienna had this problem?

few weeks