My 2011 Equinox makes a popping nose after the car has been running what is it? on 2011 Chevrolet Equinox

It is most obvious when I turn the car off but it also occurs at stop lights when the car is running. Seems to be coming from the under the rear area of the car. Any ideas?

Asked by for the 2011 Chevrolet Equinox
should be under factory warranty.
Hi yes it is ... I took it to the place I purchased it and they couldn't reproduce it they said cause they couldn't drive it further than 15 miles so told me to take it to Chevrolet.