The generation of strong splashes of the field of an electromagnetic wave during reflectionless blooming of a layer of a nonuniform medium is reported. The wave amplitude can increase by an order of magnitude and more depending on the starting parameters in the region of splashes. The amplitude of the electromagnetic wave considerably increases in the region of field splashes so it is necessary to take into account the effect of nonlinearity. It is observed that the thickness of the splash region substantially decreases, while the amplitude of variations of nonlinear permittivity substantially increases. The substantial qualitative difference for subwave splashes of the profiles of the wave vector and effective permittivity should be noted. The relation of the amplitude of the field of the electromagnetic wave to the effective permittivity is described by a nonlinear equation.