It is possible to cover your popcorn texture with ceiling tile. The worst part is finding the ceiling joists to nail your furing strips to to staple and glue the tiles to. If you have a good stud finder it is not to bad. Scraping the popcorn texture off first is still the best to ensure a good flat surface. Spray down with a garden sprayer let set for about 15 minutes then take a wide drywall knife and peel it right off. I just cover everything with painters plastice including the floor then you can just fold up the plastic and carry off the mess. If you just have a spot to patch you can make a tent around the area buy using push pins fastening the plastic to the ceiling and blow on new lightling feathering it out onto the old. Takes little time and saves money by not have to do whole ceiling. You can also add your paint right in with the texture to kill two birds with one stone. Just add about a quart of paint to one bag of texture. This is a nice short cut. It also makes your texture more durable from getting hit and brushed off.