Most modern homes have kitchen and bathroom cabinets with boxes that are made of particleboard that is covered with wood grain plastic veneer. The greatest shortcoming of particleboard is that its easily damaged by water. Even after the first time that particleboard comes in contact with water, it is significantly weakened and swells in thickness. Normally the veneer protects the particleboard against water , but water still can seep in at the joints at the bottom of the cabinet.
What often happens after a few years is that the bottom falls out of the sink cabinet because moisture from leaks or spills keeps seeping in the joints at the bottom and weakens the board.
There is a simple solution that can easily double the life of a kitchen or a bathroom cabinet. When the cabinet is new or is still in good shape, take a tube of clear acrylic latex caulk with silicone and run a thin bead along the bottom edges. This seals off the pathway for the water to attack the unprotected particleboard and prolongs the life of your cabinets.