One of the perils of using cheap window tint for your car is they tend to get damaged after a 3-4 years. They either fade to an undesirable brownish tint or develop the dreaded bubbles underneath. For my car, it's the latter.
When either of that happen, you might want to just rip off the tint from your windows. Now, not many people knows there's a proper way to take the tint off your windows. Do it the wrong way and you'll have this ugly gooey mess on your windows.
There's a few way to remove this glue from your car's windows. You can use a combination of sun light, plastic bag, ammonia, steam iron, razor blade or hair dryer. If you are using sun light and plastic bags, the tint film must still be attached to your windows or else it won't work. I can't find ammonia for sale anywhere and I tried using a hair dryer to heat up the glue and wipe it clean but it's a painfully slow process.
So in the end I used the good old razor blade and thinner solution. You start by slowly scrapping the tint glue off the windows using the razor blade and then wiping it clean with the thinner solution. For your rear windows, be careful not to scrap off the heating strip as well. From my experience, this method is also painstakingly slow and tedious but it works perfectly. After a good 1 hour and half scrapping the glue, I managed to clear out my entire rear windows. The blades will be blunt after some time so make sure you buy at least a box for each window pane.