We've all heard of the three states of matter: solids, liquids, and gases. Recently someone told me that there is some sort of state of matter between a liquid and a gas. Does anyone know what he's talking about?
It really depends upon your definition of state.
And also what you mean by between a liquid and a gas. Both are fluids, a liquid is constrained by its surface in a way that a gas is not.
Some might say that water droplets dispersed in the air (clouds) correspond to your requirements.
Others might point to the adsorbed state of gas molecules on charcoal.
Of course it is easier to find examples where the rheology allows intermediacy between solid and liquid eg glass - the vitreous state.