In a medium saucepan, add in the blueberries and sugar. Place over medium heat and stir to combine. Using the back of a wooden spoon, press the berries against the sides of the saucepan to pop them. This will help get the juices flowing.
Once the juices come up to a boil, let it boil for 3 minutes, stirring constantly.
Pour the berries and juice through a fine mesh strainer. Press the berries until all of the skins and very little pulp is left in the strainer.
Pour the juice into 7 of the slots in the mold. Place the lid on the mold and sticks in.
Place into the freezer overnight or until firm.
Run warm water onto the bottom of the popsicle mold for about 30 seconds. Remove the popsicles from the mold.
Place the popsicles into a freezer bag or freezer-safe container and store in the freezer.