As was mentioned in some comments, water is a mostly incompressible liquid - that is, if you want to make the volume of water smaller, you need to apply a LOT of pressure. How much pressure is given by the bulk modulus, which for water at room temperature is about 2.2 GPa. Comparing with the bulk modulus for air at 1 atm, it is about 100 kPa - 2200 times smaller.
So if you try to reduce the volume of water, it will try very hard to find another place to go, rather than occupy a smaller volume. One way to think about it is this: if you have a small car that can seat four people, and you need to transport a large suitcase in it, you might end up with somebody sitting on the roof. That is the situation of water: there is not a lot of space between the molecules. By contrast, an ideal gas can be thought of as a large bus with four people in it: if you need to transport a suitcase, somebody may have to sit a little bit close to someone else - but nobody has to sit on the roof.
We can do the same analysis a bit more formally by considering the microscopic picture. If you have an elastic ball bouncing back and forth between two walls, then the average force on each wall is going to depend on the speed of the ball, and the time between collisions - which is a function of the distance between the walls. If the walls are closer, the ball bounces more frequently, and you have a higher average pressure (more collisions with the wall per unit time). That is the "ideal gas" situation.
For a liquid, the molecules are so close together that they experience a significant attraction - the Van der Waals force. This means that the molecules cannot be considered as individual balls that spend most of their time flying around without hitting anything. And because they are so close together, if you reduce the distance even by a tiny amount, the repulsive force increases significantly - much more than for a gas. As is seen by the difference in bulk modulus.
So the ideal gas law cannot be applied to liquids. It would have had to be called something else, I suppose.