In this paper, strongly pseudomonotone quasi-variational inequalities are investigated. We provide sufficient conditions for existence and uniqueness of solutions of strongly pseudomonotone quasi-variational inequalities. We present some error bounds in terms of residual and regularized gap functions. The global exponential stability of equilibrium solutions of a projected dynamical system for strongly pseudomonotone quasi-variational inequalities is investigated. Strong convergence and error estimates for sequence generated by the (modified) gradient projection method with suitable choices of stepsizes are also studied. Some examples and numerical experiments are provided to support our main results.