Its happening to me too. It goes through a number of redirects before going to an advert or a popup asking me to open the app store. Sometimes it happens when I click through to a forum thread, sometimes it happens a short while after a board threadlist has opened. At first I thought I was just clicking on the banners which are slow to load and therefore appear under where I'm about to click, but I'm fairly sure it's not that. I'm logged in and running the latest Chrome browser on Android 5.0, I don't have a desktop to do any more analysis on.