In a large saucepan of salted water, bring the shrimp to a boil and cook until opaque, 2 to 3 minutes; drain.
Halve the shrimp lengthwise and place in a large bowl. Add the cucumber and toss with the lemon juice and oil.
Dividing evenly, top the bread with the hummus and the shrimp mixture. Serve with chips, if desired.