At the time of death, fire burns the gross body, and if there is no more desire for material enjoyment the subtle body is also ended, and in this way a pure soul remains. This is confirmed in Bhagavad-gita (tyaktva deham punar janma naiti). If one is free from the bondage of both the gross and subtle material bodies and remains a pure soul, he returns home, back to Godhead, to be engaged in the service of the Lord. Tyaktva deham punar janma naiti mam eti: he goes back home, back to Godhead.
Source: A.C. Bhaktivedanta Swami Prabhupada (2014 edition), “Srimad Bhagavatam”, Ninth Canto, Chapter 6 – Text 54