How would you express spontaneous conclusions in a song

Explanation:

Alt-J's first album ends with the song Taro -- a song whose outro leaves a very strong impression on me. The outro sounds like a very fitting ending to any album, because the music simply gives me that aforementioned sense of accomplishment, as if arriving after a journey. When I first heard the outro, I immediately knew that this was the last song on the album, simply because of some qualities in the music.

My question: is there a certain composing technique that causes the music to convey this sensation? If so, what is it? I am very interested in attempting to write something similar, just because this intrigues me to no end.

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