This one turned out to be fairly easy. The tube in question is an overflow tube. It's snaps into the plastic where you pour the windshield wiper fluid in. I guess it serves as an overflow if you pour too much fluid into the system.

Hello, I recently got my 2007 Volvo XC90 V8 back from the dealership for an oil change. They told me they filled all the fluids. I noticed my windshield wiper fluid went low rather quickly. I filled it back up and noticed it was leaking out of a black hose/tube next to the resevoir for the washer fl...