Bleach dispenser drains when filling

Once in awhile when I fill the bleach dispenser it drains (siphon is more like it) the bleach into the washer while I am filling it. It will drain completely and if I try to pull the dispenser out I've got bleach running everywhere. No water in the bleach dispenser prior to filling. After the bleach has run out, but not completely, I remove the dispenser, remove the top off the bleach dispenser and everything is clear and clean.

I just think something is causing the bleach to siphon out on it's own but it makes a mess checking everything. It will not do it the second time after removing the bleach dispenser cover, may be weeks before it happens again.