Some web pages open pop-up windows which they hide behind the main browser’s window. This can be frustrating because when they get discovered behind the stack of open windows one cannot possibly know where they came from.
These pop-up windows are usually advertisements and may look like this:
If you are using Chrome or Firefox you can find out which page has opened a pop-up by right-clicking on the pop-up’s main area and selecting Inspect. In the window or tab that opens select the Console tab.
In the console type:
and press Enter. Your browser will tell you which page has opened the pop-up:
I hope this helped you