A water table will exist when the soil is completely saturated, and a bore hole will fill with water.
A perched water table can be formed when an impermeable clay layer under a sandy soil stops drainage. Water may either pond on the clay layer, or drain horizontally.
It is also possible to have a perched water table with a coarse sand above a fine sand. This sounds contradictory, but the phenomena is used in the construction of golf courses and can occur in natural soil profiles. The pore water is stopped from draining by surface tension set up between the fine-to-coarse layers - the coarse sand may not act as a drain. The behaviour is dependant on the ratio between the pore sizes of the two soil layers. The ratio is similar to that required when designing sand filters in earth dams that stop soil particles being washed out.