Rotary scrapers were made for this: https://www.fishersci.com/shop/products/rotary-scraper-100-250-500ml/501354676
Otherwise, if your solute is really precious and you don't want to lose any product at all, take it out just before it's dry, put it in a tray or other wide, flat container that will be easy to collect solid off of, and finish the drying in a vacuum oven. https://labovens.net/collections/vacuum-ovens