Very Interesting...
Good problem solving guys..
Yeah plastic bottles, pop cans, anything sealed that is changing pressure.
In the older planes, popping was pretty common..if you ever saw a pic of a plane, from the outside at altitude, you could see the skin expansion..
In a Citation...never saw this...if the windows are moving back and forth somehow on the screws, then get those checked, that's creating wear that shouldn't be there... Many times the windows don't make inspections, because they are cracked at the connection points, which made me wonder if the techs tightened them down to too much to begin with....but,...I am starting to wonder now if the pressurization is putting enought stress on those screws to pop this and that.crack those connections...again, never heard noises...
If you can isolate this, that's best....not coming from your storm window?
Another idea is that the skin on your side is 'soda canning', again, expansion of the skin...