In a large pot, bring the water and sugar to a boil over high heat. Reduce the heat to low and simmer the mixture for 15 minutes. Remove from the heat and allow to cool to room temperature.
Add the orange juice and lemonade concentrates to the simple syrup, and stir to combine. Add the bourbon and again stir to combine. Transfer the mixture to a large freezer-proof container and freeze for at least 8 hours.
When ready to serve, fill glass halfway with the slush, then top it off with your carbonated beverage of choice.