Even in the bouncing ball case, Newton's third law doesn't give the whole answer. If I drop a rubber ball and a brick onto the floor, the ball will bounce, while the brick won't. The equal and opposite reaction is enough to stop the ball and brick from moving. The ball gets an extra "kick" because it compresses when it first strikes and then springs back to its original shape, pushing off the ground with additional force.

You can do a basic analysis of this situation with the law of conservation of energy. Without going into details, the height something can reach when gravity is pulling down on it depends on the energy it has divided by its mass. Since the mass of the tea drops is much much smaller than the mass of the sugar cubes, the total height they can reach is higher than the sugar cube's starting point.

Here's the more detailed analysis:

If you hold something off the ground, it has **potential energy**, which is given by U=m*g*h, where m is the mass of the object, g is a constant that specifies the strength of earth's gravity, and h is the height you've lifted the object. When it falls, this energy changes into **kinetic energy**, which is the energy of moving objects. When it bounces, it rises and slows down: the kinetic energy becomes potential energy again. At its peak, it can not have gained energy (energy is conserved), so it can't get any higher than it was when you dropped it. This explains why a bouncy ball never bounces higher than you dropped it.

Ok: so what about a sugar cube in water? Well the sugar cube has some potential energy due to gravity that depends on its height and mass. When it hits the water, it has converted that potential energy into kinetic energy. However, when it enters the water it slows down, so it loses energy. This energy lost by the cube is transfered into the water: some of it as heat, some of it as waves, and some of it will kick droplets back out of the water. Remember that the potential energy of something is equal to m*g*h. Even if they're not getting all the energy from the cube, if these water droplets have a very tiny mass, then you can multiply them by a large height, h, and still have a small total energy for the droplet. Put another way, if you have a water droplet kicked out of the tea that has energy E, the height it will reach (assuming it splashes straight up) is h=E/(m*g). So for a fixed energy, if you take a very small mass of the water, it can reach a great height.