What is the clearest empirical evidence for interactions between molecules?

There are several spectacular visual experimental evidence of interactions between molecules: 1). Sticking of lead cylinders when pressed, requiring, in the future, significant efforts to break them. 2). The phenomenon of wetting. A glass plate located on the surface of the water requires some effort to lift it from this surface. 3). Capillarity phenomenon. 4). Surface tension. In zero gravity, the liquid takes the shape of a ball due to this phenomenon.5). Elasticity of bodies under compression and tension.