To make the jam: In a bowl, combine the thawed raspberries, agave, chia seeds, and salt. Stir for about 1 minute, until the raspberries are mostly broken up, the agave nectar is dissolved, and the chia seeds are distributed evenly throughout. Cover and transfer to the refrigerator to firm up for at least 2 hours, or up to overnight. The jam will keep in an airtight container, refrigerated, for up to 1 week. Stir once more before serving.