A soap bubble is created in the same way the detergents reduce the surface tension of water.
Pure water molecules attract each other strongly and will always pull together to form a droplet rather than a film. Detergent molecules reduce the attraction between them but the water molecules retain enough attractive force to create a film.
When a child blows a bubble, the film stretches and forms a sphere. As the water evaporates, the bubble bursts.
Picture Credit : Google