A nanobubble generator, a nanobubble-containing liquid solution comprising a substantially high concentration of nanobubbles, a system and methods of producing the nanobubble-containing liquid solution. The nanobubble generator includes an inflow portion for receiving a source liquid solution, a series of at least two sequential cavitation zones and shear planes to treat the source liquid solution and producing nano-bubble containing liquid solution, and an outflow portion for releasing the nanobubble-containing liquid solution.