We report the formation of giant Pluronic L121 vesicles with diameters of the order of 200 pm obtained by a previously unreported mechanism that occurs during the solvent evaporation method of vesicle formation. We begin with a water oil water double emulsion that is stabilized by dissolving the commercially available triblock copolymer Pluronic L121 in the volatile oil-phase. During the evaporation, the oil phase spreads on the surface of the continuous aqueous phase, leaving behind the aqueous inner droplet of the double emulsion droplet that eventually yields the vesicle. The spreading of the solvent mixture of the oil phase is induced either by the rapid ejection of the inner droplet out of the double emulsion droplet, or by the spreading of the oil phase of a neighboring emulsion droplet.