Hi and thanks for your question.
Popping sounds in the ear can be a sign of an inner or middle ear infection. Fluid can become trapped behind the ear drum and this can change the pressure in the ear, which can lead to different symptoms. Does it pop spontaneously or can you elicit it by doing something? Do you have any ear pain, decreased hearing in that ear or sense of fullness? Also have you had a cold or flu recently?
You should visit your doctor and have him/her take a look inside your ear to make sure there is no infection.