Question

How would we know that the concentration of water is high in given solution or the particular given cell

Answer 1

The cell will swell up
When the solute (or salt) concentration outside the cell is low and the water concentration is high than in the cell. So the water will move from its high to its low concentration. That is to inside the cell and hence the cell will swell. This movement of water is called endosmosis.
if the cell shrinks,then the water concentration is more in the cell