Wash the red beans, and boil them in a large pot with 4 cups of water over medium heat about 5 minutes. Strain, then return the beans to the pot. Add 2 cups of fresh water, and cook for 10-15 minutes if using a pressure cooker. Or cook in a regular pot for 1 hour over medium-low heat, adding water occasionally to keep the beans submerged. Press them with your fingers to check if they are soft enough to mash. Once softened, boil off most of the remaining water.
When water is almost gone, mash the beans halfway with the back of a spatula. Add the sugar in three parts, stirring and cooking over medium low heat for 5 minutes in between each addition. Finally add 1 1/4 cups (300 ml) of water to the red bean paste and simmer to thin it out for a minute. Remove from heat.
Pack the thinned red bean paste into ice cream bar molds. Insert plastic or wooden sticks into them. Place them in the freezer for one day to allow them to freeze and set completely.
Pour tap water over the molds, then pull the sticks to remove the frozen popsicles.