Concentrated urine is hypertonic to blood?

OK in this book it says that reabsorption (substances such as glucose and salts being returned from nephron to the blood) results in concentrated urine which is hypertonic to blood. Wouldn't reabsorption of salts cause the urine to become LESS concentrated and thus become HYPOtonic to blood? OR if pive diffusion of water occurs as the book says it does, wouldn't salt concentrations balance out and the nephron filtrate and blood would be isotonic? Either way it boggles my mind how reaborption could cause a hypertonic filtrate.