Burned my sub up

Well Ive always had systems in my vehicles and Ive finally burned up a sub woofer. I dont really know how i did it. Ive gotten some ideas from reading how other people have done it.

I had a Punch P3 slim 12" in a ported box for my Tacoma, but Ive moved it into my gas car's trunk. it was being powered by my alpine MRP-M500. The amp over powers the sub my 100 watts RMS. Ever since moving my speaker into my car i have felt it wasn't playing as loud. so i adjusted my amp from the setting it was at in my truck. the adjustment was turning up the bass boost 6 DB. sounded better than ever. NO distortion!! well i was playing with the head unit and dropped my FQ filter from 80 Hertz down to 60. Turned up a Lil Wayne song and then came a funny tapping sound like something had been lied in the cone and the sub was bouncing it around, then smoke. took it out cant see any physical burn or damage just looking externally, but the noise is still present! no more smoke but the sub is done

so between the stuff Ive read I'm leaning to wards the FQ drop with the added boost from the amp made the sub try to carry notes beyond its capabilities. what u guys think?