Making amorphous sugar - bubbles...

Hey all..

I'm trying to freeze dry sugar which I read will make amorphous sugar which is a kind I want to use in confection. I made a one-to-one sugar syrup and freeze drying them but have noticed that it's severely bubbles up to the point that it's hitting the front acrylic, making a huge mess inside.

Does anyone have any tips on how to freeze dry this without creating such large bubbles? Add less water? Just make it a paste instead of a one-to-one syrup?