What are the connotations of "ba'Boker ba'Boker"?
Rashi (117b): They collected the Manna in the early morning.
Targum Yonasan: Up to four hours, when it became hot.
Seforno: They collected it each and every morning, to prevent it from melting.
What happened to the leftover Manna?
Rashi #1 (citing the Mechilta) and Targum Yonasan: When the sun became hot 1 it melted and turned into rivers, 2 from which the deer and the nations of the world drank and enjoyed the taste of Manna 3 (Rashi) 4 .
Rashi #2 (in Iyov, 6:14): It disintegrated.
After four hours into the day (Targum Yonasan).
That flowed into the sea (Targum Yonasan).
Upon which they realized the good fortune of Yisrael (Rashi). According to Targum Yonasan, after various specious of Kasher animals would drink from those rivers, Yisrael would catch those animals and eat them (tasting the taste of Manna).
See also Ba'al ha'Turim.