Put sugar, water, and blueberries in a medium-size saucepan and bring mixture to a boil. Once boiling, lower heat and let simmer for about 10-15 minutes, until blueberries have burst and mixture has thickened.
Strain mixture through a fine mesh strainer into a bowl, being sure to press down on the berries to extract as much juice as possible. Keep syrup in bowl or pour into a mason jar and place in fridge to cool completely before using.
Video
Notes
When stored properly in an airtight container, blueberry syrup should stay fresh for about a month.