Desvanecer means 'to vanish' or 'to fade away'. It's a beautiful and somewhat dramatic verb that evokes a sense of dissolving or disappearing.
In "Fuego En El Fuego," Eros Ramazzotti sings, "Quiero morirme en tus labios desvanecer" (I want to die on your lips, to vanish). This line uses desvanecer to express an intense desire to be completely consumed by passion, to the point of losing oneself entirely in the embrace of another. It's a poetic way to describe ultimate surrender and intimacy.
Eros Ramazzotti opens with the line "Fuego en el fuego" ("Fire in fire"), and that image carries the whole song: two people whose heat has already merged into one fire. The verses circle through wanting and confusion, asking "¿Qué es lo que quieres tu de mí?" ("What is it you want from me?"), before the chorus drops the questions and just states it plainly: "Estamos quemándonos" ("We're burning").
The bridge gets more physical, all skin and warmth, with "Llenaré mi piel de tu calor latino" ("I will fill my skin with your Latin warmth"). By the last chorus the metaphor has stopped feeling like one at all, and the track ends with someone calling out a name over the mix, "Carlos, estamos quemándonos" ("Carlos, we're burning"), like it was cut live off the studio floor.