Unknown way to play harmonics on violin

Описание: Today while I was warming up and practicing my (uneven) spiccato on open strings, I discovered a really weird sound phenomenon. If I tilt my bow hair and use a broader stroke on the open string, the violin plays the harmonic that's one octave above. I don't know if it's my rosin/strings, contact point, or some kind of physics thing. It also seems to not work quite as well on the other 3 strings. Leave a comment if you think you know what's going on!