Some women have gland tissue along their reproductive tract and urethra. This gland tissue, referred to as Skene's gland (or female prostate), produces semen-like fluid, except without the sperm. It's an alkaline, water-based fluid.
The Skene's gland is also thought to play a role in the G-spot (better known as the Grafenberg area among researchers).
Recent research has found, unfortunately, that not every woman has this glandular tissue in a way that allows ejaculation upon climax - but some actually do.
|Female genital anatomy, by Nicholasolan, Wikimedia|