When the stove is first turned on heat is transferred first by conduction between the element through the bottom of the pot to the water. However, eventually the water starts bubbling - these bubbles are actually local regions of hot water rising to the surface, thereby transferring heat from the hot water at the bottom to the cooler water at the top by convection. At the same time, the cooler, more dense water at the top will sink to the bottom, where it is subsequently heated. If the low pressure region was originally created by heating of the material, one sees that movement of material in this way is an example of heat flow by convection. An important example of convection currents that can be interpreted in this manner is the creation of breezes over land masses next to large bodies of water.
Water has a larger heat capacity than land, and subsequently holds heat better.
It therefore takes longer to change its temperature, either upward or downward. Thus, during the day the air above the water will be cooler than that over the land. This creates a low pressure area over the land, relative to the high pressure area over the water, and subsequently one finds breezes blowing from the water to the land. On the other hand, during the night water cools off more slowly than the land, and the air above the water is slightly warmer than over the land. This creates a low pressure area over the water relative to the high pressure area over the land, and breezes will blow from the land to the water.