וַיִּלְקְט֤וּ אֹתוֹ֙ בַּבֹּ֣קֶר בַּבֹּ֔קֶר אִ֖ישׁ כְּפִ֣י אָכְל֑וֹ וְחַ֥ם הַשֶּׁ֖מֶשׁ וְנָמָֽס׃
And they gathered it morning by morning, every man according to his eating; and as the sun waxed hot, it melted.
Read kabbalistic (mystical) interpretation of Exodus 16:21: and classical mystical sources.