"...popping sounds when going on a new webpage/website"
I appreciate you say you've looked under "Sounds" but you haven't said what you checked for or what you did. Revisit Control Panel -> Sound -> "Sounds" tab -> "Program Events" section -> "Windows Explorer". The entries relating to sounds whilst navigating webpages are called Start Navigation and Complete Navigation. If a sound has been assigned to those actions, click the "Test" button, and if you hear that pesky popping noise, set its sound to "None".
Or you could simply save the current Sound Scheme, set it to "None" to turn off all Windows sounds, and see if that helps.