Just in case I can't find an open bar or bakery, I usually carry chocolate, muesli bars, bananas, nuts and dried fruit and a packet of light, sweet bread rolls. Also useful are the 'long-life' packs of yoghurt drink, which does not need refrigeration.
I have seen pilgrims boiling eggs in the albergues for breakfast the next morning. And if the albergue has a fridge you could buy some cheese and salami to eat before walking.