This is caused by a new 'feature'which is supposed to save power by powering down the sound chip when not in use.
To prevent it from doing this thus preventing the popping sounds edit your:
(I prefer to use vim. Nano is a good alternative)
bash$ sudo vim /etc/modprobe.d/modprobe.conf
and add the line:
options snd-hda-intel power_save=0
then reboot, and your issue should be fixed.
This only works for intel chips using the snd-hda-intel driver.
To look for options for other sounds cards with the same issue ( I haven't heard of any) open a terminal and type:
replacing MY-MODULE with the sound module used.