These get you there partially, as in you'd see when it's complete but not when it changes to any other % other than 100. These may be off in your instance and therefore not an option to opt in or out of in you own profile:
If you have Fusion, I'm sure this could be a scenario (notify project owner when task % in projects you own changes).
If you don't have Fusion, and neither notification helps, try a journal entry report to see if you can isolate task % complete changes on projects you own.
If this helped you, please mark correct to help others : )