I have had my 2018 Accord Touring in for service for a popping noise on the passenger side which sounded like it was coming from the rear. They replaced the strut and front lower control arm saying they had a tool which senses noise and that is where it was coming from. Anyway, after the third time in the service manager went for a ride with me and he discovered when a passenger was in the seat it popped more often when hitting a bump or making a turn. He found the issue right away. It was the passenger seat track. They ordered another seat track. Got to say they were really trying to find the issue as they could hear it sometimes even without a passenger in the seat. Just thought I would share just in case anyone else had such a noise.