We report on the dynamical formation of self-bound quantum droplets in
attractive mixtures of 39K atoms. Considering the experimental
observations of Semeghini et al., Phys. Rev. Lett. 120, 235301 (2018), we
perform numerical simulations to understand the relevant processes involved in
the formation of a metastable droplet from an out-of-equilibrium mixture. We
first analyze the so-called self-evaporation mechanism, where the droplet
dissipates energy by releasing atoms, and then we consider the effects of
losses due to three-body recombinations and to the balancing of populations in
the mixture. We discuss the importance of these three mechanisms in the
observed droplet dynamics and their implications for future experiments