Thanks for asking the query,
Clicking or popping sound in the ear while opening and closing of mouth can be due to Temporomandibular joints disorders.
, habit of grining teeth at night, Temporomandibular Joint defects can lead to such sounds.
As you have mentioned you have no ear problems, I would suggest you to visit to an Oral and Maxillofacial Surgeon and get checkup done,
Take an OPG x-ray to check the status of the joint.
Hope this helps out.