I only really understood my native language syntax until I studied foreign languages. "English Grammar for Students of German" was probably the best thing that happened to my English skills.
Same here. Had no idea why English grammar worked until I studied German. Then I suddenly had solid mechanics backing up my knowledge of English, not just immersion-driven intuition (which is inscrutable, deep-down-- "cuz 'to whom' sounds better, I guess, maybe.").